President Obama emerged from offstage to bear hug Bill Clinton at the Democratic National convention tonight moments after Clinton giving a rousing speech nominating Obama for reelection, calling the president a man who is "cool on the outside," but "burns for America on the inside."

Once a political adversary, Bill Clinton tonight went to bat for the president, playing the dual parts of professor and preacher, firing up the crowd and explaining just how Obama has succeeded in working to fix a flailing economy.

Clinton strode to the podium to the strains of his old presidential campaign theme song "Don't Stop Thinking About Tomorrow," and a roar of applause from Democrats who remember the boom times of his two administrations.

"I want to nominate a man cool on the outside but burning for America on the inside.... I want Barack Obama to be the next president of the United States and I proudly nominate him as the standard bearer of the Democratic Party," Clinton told the Democratic National Convention in Charlotte, N.C.

He complimented Obama for his ability to work with those who ran against him, saying Obama appointed several people to top jobs who had supported Clinton's wife Hillary Clinton during their bitter battle for the Democratic presidential nomination four years ago.

"Heck, he even appointed Hillary," Clinton said. Hillary Clinton is Obama's secretary of state.

Articulating the successes of the Obama administration in 30 minutes more concisely and energetically than the Obama campaign has in six months, Clinton said President Obama's policies were working to fix the economy.

"I understand the challenge we face. I know many Americans are still angry and frustrated with the economy. Though employment is growing, banks are beginning to lend and even housing prices are picking up a bit, too many people don't feel it," he said.

"No president – not me or any of my predecessors -- could have repaired all the damage in just four years. But conditions are improving and if you'll renew the president's contract you will feel it," he said.

The Romney campaign has made a point to ask voters if they are better off today than they were four years ago. Clinton twice answered Romney's question head on and in the affirmative.

"Are we better off than we were when he took office, with an economy in free fall, losing 750,000 jobs a month? The answer is yes," he roared.

Clinton celebrated Obama's signature healthcare law, pointing out that more 3 million young people are now insured and that health care spending has grown under 4 percent for first time in 50 years.

"So are we all better off because President Obama fought for [health care reform] and passed it," Clinton asked. "You bet we are," he answered to applause.

Clinton attacked GOP vice presidential candidate Paul Ryan, architect of the Republican budget plan, for being disingenuous last week at the Republican National Convention.

"When Congressman Ryan looked into the TV camera and attacked President Obama's 'biggest coldest power play' in raiding Medicare, I didn't know whether to laugh or cry. You see, that $716 billion is exactly the same amount of Medicare savings Congressman Ryan had in his own budget," he said.

"It takes some brass to attack a guy for doing what you did," Clinton said to laughs and cheers.

Clinton headlined the second night of the Democratic National Convention and he officially nominated Obama, a job typically performed by the nominee's running mate.

Obama traveled to Charlotte to hear Clinton praise and nominate him. The president stayed in the White House with his two daughters on Tuesday night to watch his wife Michelle give an emotional speech backing his character and his presidency.

Though Clinton and Obama have sparred in the past, especially during the 2008 Democratic primaries that pitted Obama against Hillary Clinton, the Obama campaign bet that the former president, a Democrat who oversaw nearly a decade of economic prosperity, will remind voters of what having a Democrat in the White House can mean for their wallets.

"In Tampa the Republican argument against the president's re-election was pretty simple: We left him a total mess, he hasn't finished cleaning it up yet, so fire him and put us back in," he said.

"I like the argument for President Obama's re-election a lot better. He inherited a deeply damaged economy, put a floor under the crash, began the long hard road to recovery, and laid the foundation for a more modern, more well-balanced economy that will produce millions of good new jobs, vibrant new businesses, and lots of new wealth for the innovators," he said.

Clinton also said that a vote for Obama represents a vote for doing what is best for the country, not just for oneself.

"The most important question is, what kind of country do you want to live in? If you want a you're-on-your-own, winner-take-all society, you should support the Republican ticket. If you want a country of shared prosperity and shared responsibility -- a we're-all-in-this-together society -- you should vote for Barack Obama and Joe Biden," he said.

Clinton's speech marks the apex of a previously rocky relationship with Obama. When Obama ran against his wife Hillary Clinton in 2008 for the Democratic nomination, Bill Clinton often jabbed Obama on the stump, even calling his campaign a "fairy tale."

Hillary Clinton, now President Obama's secretary of state and a possible 2016 contender, will not be at the convention. She is on an 11-day tour of Asia and the Pacific and is expected to be in the tiny island nation of East Timor at the time her husband takes the stage.

Democrats may be betting that Clinton will remind voters of more prosperous times under a Democratic president, but the Republicans said the former president's presence will only remind voters of Obama's failures.

Former House Speaker and onetime Republican presidential candidate Newt Gingrich told USA Today that Clinton's appearance "an enormous risk" that would remind voters of how "pathetically bad Obama has been."

GOP vice-presidential nominee Paul Ryan, campaigning today in Iowa, said Clinton would do little more than deliver "a great rendition of how good things were in the 1990s. But we're not going to hear much about how things have been in the last four years."